Indoor Heat Management

Hey gang I need some help, training in a 10x12 foot room which has 1 central AC vent as well as 2 fans positioned diagonally in front of me, and one small fan behind me blowing onto my back. In the winter I just open the window about 12-24” and it keeps the room nice and tolerable even during hard vo2 work.

However today I tried to escape the outdoor heat and humidity and did Beehive indoors, 2 hours at .7IF doing intervals from 65-75% and I was really struggling in the heat. My HR was climbing a little more than usual for the amount of intensity, but also wasn’t coming back down much when the power dipped even during the easier intervals. I had the central AC set to 74*f but the room was easily in the mid 80s, it probably didn’t help that I shut the door and basically hotboxed myself but sometimes I have to do this if the wife is home so I don’t generate a bunch of noise and smell into the rest of the apartment

In the winter it’s easy to open a window but in the summer on days like today or if it rains, I cant let cool air in through the window so wondering if I should maybe look into a portable AC unit for the room, and if so, how many BTU I’d need for the space. I’m in the US if anyone is going to recommend specific products

For a 10x12 room, just about any AC will do since you already have central AC.

Window ACs are priced proportionally to the BTU and sized accordingly as well. A small window AC will frankly be a lot easier to handle and install than a big one.

Portable ACs are more expensive but also more convenient to use. Way easier to install and you don’t run the risk of crushing an old lady 2 floors down (Happy Gilmore reference). Also, depending on hose length, you can also point the AC directly at your face, which feels amazing. There’s less of a price gap between the lower and higher BTU portable units. So if you get one of those, which would be my preference, I might suggest sizing up to 8,000 BTU.

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I was def thinking portable and not a window unit, condo association says we can’t have those anyway as much as I’d like for it to drop on our property manager (your Happy Gilmore reference was well placed)


Get a portable AC. I have an older LG.

Pretty simple - open the window when you’re using it putting the hose in, add a towel to the top part of the window to create somewhat of a seal, cool the room as low as you want. I generally start mine 30 minutes pre ride and shut the door

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@Cleanneon98 I’m glad I’m not the only one. My training options are either outside in the Florida panhandle (rarely below 85 degrees and 75% humidity), or inside a small room with a few fans and a smart trainer. I’m currently doing a polarized plan, with long rides outside and the threshold intervals inside. I’ve failed a few indoor workouts because of cooling, so I’m talking myself into buying a power meter so I can take all my rides outside. Of course, I’ll probably overheat there too and end up getting indoor AC as well :grinning:

Make sure you get that portable unit blasting cold air directly at you in such a small space. They have a habit of removing all the newly cooled air from the room and blowing it straight out the window.

Edit: I was thinking about the description of your pain cave a little more and wonder if you’ve tried partially blocking some of the other outlets in the apartment? If it’s a basic ducted system you should be able to mess with the balance and do what you want without the need for a portable unit.
If you leave the window cracked and keep the door closed the room should get pretty cold.

Portable ac unit is a game changer. If you can, let it run for an hour before you start your ride. It will make a huge difference.

I think having the door open behind you and the fans blowing in that direction would reduce the build up of heat. If the wife is ok w the noise.
2) the fan blowing on your back might be "fighting: w the one blowing on your front and reducing the cooling effect of both,

Yup, that’s been my experience. Got rid of my 3rd fan for that reason.

A new thing I’ve been doing is wetting my towel. Prevents it from getting blown around by the fan and its cooling effect is tremendous. Just make sure you air dry it when you’re done rather than just throwing it in the hamper, cuz it’ll stink otherwise.

A spray bottle with chilled water is massive as well.

I hear dual hose is the way to go, else it has to pull air from somewhere, which means it gets it from leaky spaces around doors/ windows etc…. Which means you pulling warm air into your house. I dont have one but have been looking

In my case, I set the central AC to 70 and USUALLY is running the whole time while i am on the trainer…
You just need to set it a few degrees cooler then current temp and the central AC will be blasting cold air…
in your case I would set it to 70 while you wo.

I freeze gallons of water for those hot days in the garage. Ice cold water to drink and dump on my head during rest intervals, helps a lot. Usually it’s the sweet spot intervals that get me.
I also have a dehumidifier and two big fans blowing directly on me. Good old florida summers.

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Florida Killed my love for running fall marathons…

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May not be an option, but this is one of the reasons I ride at 4:30 AM. I have the smart thermostat cool the floor off at night which helps with sleep, but also drop it several degrees before my workouts. Room still goes from 68 to 74 usually before I’m done, but that’s not a deal-breaker. I also have 4 fans. Two up front, one at the side, and one at the back. I don’t feel like they compete with each other because they can’t blow through me. It is nice to have something hitting your back since it’s a large surface area. The two in the front hit me at different heights. Main one chest level and secondary one at eye/forehead level which cools the top of my head and also gets me when I stand. I have a portable in my garage, which can cool it, but it’s usually way hotter in there, so it’s hard for me to say if it would do the job in an air conditioned space.

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Is there a reason you keep the central AC so high? My indoor routine is wake up early, put AC on 65, have coffee, mill about a bit, and get on the bike when it hits 65. Some days/workouts I would wish for a little cooler, or another fan, but usually when I get on the bike taking my shirt off and putting on my HR strap is COLD.

Granted, my wife wears tank tops and shorts and opens all the kitchen windows in the dead of winter, so I get no objections…

I am VERY jealous of those of you getting to train at 60 or 70 degrees in the summer. Where I live we’re lucky to keep the electric bill under $400 with the AC at 77 in summer. Summer workouts suck and I always go backwards in my fitness.


I went from a townhome in VA (1800 sqf) to a massive house in FL (3100 sqf)
The first month i was in the new house I set the AC to the same I had in VA 72 during the day, 65 at night.
I told coworkers that and for some reason they start laughing at me… my first bill (not full month) was almost 300!
I quickly learned my lesson…

Now I have solar panels and during the day i let temp go to 80 and at night I sleep at 70


75 is comfortable for everyday life at home so I keep it there, plus to save money :grinning:

Closed some of the vents in other rooms, and left the door open yesterday. Did some threshold work and the room was at 77* when I started, 80* when I finished. Much better


This is where investing in good fans can be critical. I live on a fourth-floor loft in an old building. As such, it can get VERY hot in the summer. AC units are essential but I don’t necessarily keep them running all the time throughout the whole apartment. I have 2 Vornado fans for my trainer. These are NOT cheap, $100 USD for each fan carries substantial sticker shock, but they are leaps and bounds more powerful than your Walmart special Honeywell fans and can save you on utility costs in the long run. I leave them running in my 16’x14 “pain cave” and it keeps the ambient temperature pretty comfortable, even more so if I keep the room darker. They are placed <12 inches from my handlebars on both sides and I can tilt them toward my torso/legs as desired. You could even go with three and place one further back or behind if you are a heavier sweater. Using an AC unit in the room drops the temperature another 10 degrees which is great, but if energy costs are a concern, the high-quality fan solution can make the room serviceable for training.
I know the TR team recommends the Lasko utility fans, I personally find that the Vornados give you more flexibility, but it’s a matter of preference on that point. Bottom line, you might be into an one-time investment between $200 and $300 but you will be able to use them for years to come and your payback in energy costs will be 2 months max.


Current setup: Wally World fan on the left, Lasko on the right